Save $500 and Have a Great Running Dirt Bike | How to Jet Your Carburetor

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Jetting a carburetor isn’t rocket science. Everyone who owns a dirt bike with a carburetor on it really should take their carburetor off the dirt bike at least once, and take it apart to see how it works. They are incredibly simple, and elegant solutions to atomizing fuel before it enters the combustion chambers of our internal combustion engines.

Lets do some VERY BASIC carburetor 101 here. Once you understand that there is an “idle circuit or Jet” that controls the fuel/air mix from closed throttle to about the 1/4 throttle position, a “needle jet” that controls the fuel/air mix from about 1/4 up to 3/4 throttle, and a “main” jet or circuit that controls the fuel/air mix from about 3/4 throttle to fully wide open, you begin to understand how making changes to those areas make a huge difference to what you are trying to accomplish.

For my money, I like to focus on getting the right “needle" in the bike since it covers the bulk of the throttle range and is where I’m mostly riding. It’s amazing how even changing the needle clip position effects the way your dirt bike runs. Move the needle clip UP/Higher on the needle to lean the mixture out, and move the clip DOWN/Lower on the needle to en-richen the mix.

Second to the needle in my book, but certainly no less important, is the idle circuit. That is where you are riding during starting out and all of the “technical stuff”. Get the idle circuit dialed in properly and your bike will not “bog” and will make a clean, predicable transition from idle, giving you the power you need to get the bike moving and keep it moving.

Once you get those first two dialed in, then comes the “main jet”. This is the one that seems to get all the attention, but really only makes a major difference when you are 3/4 throttle and up. For the type of riding I do, this isn’t the bulk of my time.

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[atcenterice]

Kyle is the Bob Ross of dirt bikes. “Let’s just put this happy little jet in right here. Careful not to over tighten now.” 😂

[gbagz]

Glad someone else is saying it. I have successfully tuned mine as well for my area.

Anyone who says that these Mikuni carburetors cannot be tuned and are “junk” are wrong and are most likely inept or trying to sell you something.

Change my mind.

[justinpeters]

wow did i learn alot wity thid video..after many years of hearing guys talk about jetting pieces finally clicked and now understand in my head ! thank you much !

[Cooldibs]

Can you make a video on how to see if your bike even needs tuning? A lot of us don’t know if our bikes are running at their full potential!

[BLSdarrin]

I slapped a JD kit in my '18 300xc and its fine, just a little turning of the air screw when the temp drops. Gotta love the spring trick, I always used a pair of needle nose vice grips, will have to remember this

[onzalimeyphillips]

Could you do a video on what you feel for or listen for in each part of the throttle to tell if it's to lean or rich?

[rodie]

I have a 17 husky te300 and got it to run pretty good but it was never perfect. Could never get rid of the mid throttle stutter. Cut holes in air box and even tried jd jetting. Bought an Lectron and couldn't be happier!!

[tjbradbury]

I ran the Lectron last season on my 2016 300 XC and just could not get it to run as well as my Mikuni. Been using Mikuni's for years on our race snowmobiles, no idea why I let the internet convince me they were inferior! Will have the Lectron up for sale next season.

[adambatchelder]

I have successfully rejetted mini mikunis for customers as a basic setup. Those 38mm Mikuni s are definitely a little big for a 250 ridden in the woods. My favorite set up is a old style kehin and lots of people who don't understand are selling them cheep off there 12 to 16 bikes. I'm not a huge fan of the lectrons I get a lot better mileage out of a kehin mainly because I can tune each circuit individually.

[Shereefe]

I ended up getting a 100 dollar JD jet kit, and it made my 300 a super tuned machine. No asthmatic throttle range. Just pull and pull harder as you need it.

[arnoholopainen]

Great stuff Kyle 😊 I’m really happy as an old fart to see someone is still interested in basic skills of dirt riding.

[whiskeythrottledave]

I just move my $500 lectron from bike to bike. Then I don't have to piss around with jetting ever time I buy a new 300 xc. To me it is worth it.

[qtubin]

Tip. At 11:11 Pinch that cable with some vise grips, preferably needle nose vise grips, where your left hand is pinching it. Spring fully compressed exposing as much cable below it as possible. This way the spring can stay on the cable and make re-inserting the cable much easier without having to twist the spring on.

[FeenixRyzing]

You hit the nail on the head Kyle! Jetting a carb isn't rocket science and most people, I believe, just get intimidated by it. You really don't need to buy an aftermarket carb.
For me, I've just gone out and purchased the JD jetting kit for my bikes for under $75 and then fine tune it from there. Since I live at 5, 600' I had another needle with a preset clip along with jets in my fanny pack so I could swap out if the elevation dictated. 20 minutes is all it took me to swap over.

Of course, fuel injection changed that one on my 2017 lol. Great Vid!

[dino]

i watched so many videos and did a lot of research on jetting and i found the best way is to refer to your owner's manual. i was a running a 15 pilot and a 180 main and i noticed my bike kept bogging then i found out that Suzuki recomends a 30 pilot and a 210 main.

[thorstenwanoth]

Orange patient undergoing surgery in front of blue banner in backdrop appreciated in the closing shots - cool vid. This is the kind of stuff that I grew up on and I see nothing has changed in the last 40 years of carburetor tuning. Good to get the new crowd knowing what to do. ThumbsUp.

[ponydown]

Thanks for the video. I never seen the spring trick you did. I'm always learning something new.

[danielorourke]

Kyle, great video, my bike has a throttle position sensor. When i went to change the needle I noticed this extra metal piece over the slide. Just making sure that the proper way to reassemble is to have it sitting over the slide when doing the reassemble operation. Thx for sharing your experience

[fgtb]

You do an excellent job of working and talking at the same time.

[VA-NJdevilsfan]

Appreciate the CYA/cover your butts, I watch your videos with my kids (4 and 7) cause of stuff like that!